publisher多摩The purpose of research is to analyze the relationship between the water cutoff of the stricken area which was caused by Tohoku Earthquake and the informal supportive ties with special reference to the water supply. Urayasu City is exemplified in terms of people in need of the water supply. The significant finding is that the informal networks such as friends' assistance, parental house and public bathes mainly contribute to the stopgap help of sufferers in addition to the cascading relief of municipality. The research concludes that the mesh-like invisible but unofficial network is needed to rehabilitate the water supply in the grave natural disaster which typifies Tohoku Earthquake. The research is a stepping stone to investigate divergent cooperation in the perilous natural havocs.